In the Colt, every part performs at least two totally separate functions, neither of which is related to the other.
Make a small change "here" and something totally unexpected happens over "there".
The old Colt action is somewhat rightly known as a "watchmakers gun".
This is why so few of todays gunsmiths either know how to work on the old Colt action, or are willing to take one in.
On little error and the gun owner is S. Out of Luck...no replacement parts as in S&W. Thankfully, my PPS still functions, albeit with a very heavy double-action trigger pull.